knowledge comes from practice is known to all.A. IfB. WhatC. WhereD. That

问题补充：

knowledge comes from practice is known to all.

A. If

B. What

C. Where

D. That

答案：

A. If

B. What

C. Where

(答案→)D. That

解析：考查主语从句：分析句子可知is是谓语，前面的句子是主语从句，因为主语从句是完整的句子，用that连接主语从句，而且不可以省略，句意：知识来自于实践是众所周知的。选D。